1. Field Of The Invention
This invention relates to an enclosed trailer for attachment to an over the road truck. More particularly, this invention relates to a trailer of the foregoing character each of whose opposed side walls is formed from a longitudinally extending series of vertically oriented, relatively thick, relatively low density rectangular metallic plates.
2. Description Of The Prior Art
Conventional enclosed trailers have opposed side walls, each of which is formed from a longitudinally extending, vertically oriented series of relatively thin, aluminum alloy sheets with overlapping side edges. Each of the joints or seams that is formed by the overlapping side edges of an adjacent pair of sheets is reinforced by a relatively deep post, which is usually of a generally hat-shaped configuration, either on the inside or the outside of the side wall and in alignment with the overlapping edges of the adjacent sheets. A side wall of this construction is relatively light in weight for a suitable level of strength and rigidity, but is also relatively thick, in a side-to-side direction, because of the required depth of the reinforcing posts. This thickness comes at the expense of the internal width of the trailer, because overall trailer width is usually limited by applicable statutes and regulations for towing a trailer over public roads and highways. As a consequence of such a limitation on internal trailer widths, the trailer payload is limited when freight volume is the limiting loading factor, as it often is when the trailer is used to transport low density merchandise.
It is known that the internal width of a trailer can be increased by using relatively thick metallic or composite plates in the construction of the trailer side walls, in place of the relatively thin metallic sheets of the aforesaid sheet and post construction, notwithstanding that this plate wall construction adds to the weight and initial cost of a trailer. Such plates add greater strength and rigidity than the relatively thin sheets of the sheet and post type of trailer construction as described above, and as a consequence of the greater strength and rigidity of the plate wall construction, it does not require the reinforcing posts of substantial depth of the sheet and post construction. U.S. Pat. Nos. 4,810,027 (Ehrlich), 4,904,017 (Ehrlich) and 4,940,279 (Abott et al.) describe various types of plate wall trailers which are known in the art. While the constructions of the trailers of the aforesaid patents do utilize external reinforcing members in the plate wall constructions thereof, the reinforcing members of these trailers can be substantially less deep than the reinforcing posts of a sheet and post trailer of comparable size, and, when the edges of the adjacent plates in an adjacent pair of plates of a plate wall trailer are not overlapped in accordance with the teachings of the aforesaid patents, the side wall of a plate wall trailer will be substantially thinner than its counterpart in a sheet and post trailer, thus providing greater internal width for a given trailer overall width. Unfortunately, in the plate wall trailers of the aforesaid U.S. patents, the reinforcing members of the trailer walls are not directly connected to the longitudinally extending beam at the top of each wall. Thus, the reinforcing members do not contribute to the overall rigidity of the trailer structure as effectively as they would if each of them had sufficient extent to overlap and be riveted, or overwise rigidly joined, to the longitudinally extending beams at the upper ends of the trailer side walls.